Khan.scratchpad.disable(); To move up to the maestro level in her piano school, Ashley needs to master at least $168$ songs. Ashley has already mastered $10$ songs. If Ashley can master $9$ songs per month, what is the minimum number of months it will take her to move to the maestro level?
Explanation: To solve this, let's set up an expression to show how many songs Ashley will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Ashley Needs to have at least $168$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 168$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 168$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 9 + 10 \geq 168$ $ x \cdot 9 \geq 168 - 10 $ $ x \cdot 9 \geq 158 $ $x \geq \dfrac{158}{9} \approx 17.56$ Since we only care about whole months that Ashley has spent working, we round $17.56$ up to $18$ Ashley must work for at least 18 months.